关于Java技术在嵌入式系统中的应用研究

随着技术的进步,嵌入式设备正变得流行起来;另一方面;Java的安全性,跨平台性以及其它众多优点使得它非常适合于嵌入式系统,本文探讨了基于Java的嵌入式系统的各方面问题,从中可以看出Java在嵌入式设备中的巨大应用潜力。     

嵌入式系统中Java技术的应用

随着技术的进步,嵌入式设备越来越流行,而Java以其面向对象、安全性、可移植性等诸多传统编程语言无可比拟的优点,使得它在嵌入式系统领域得到了越来越广泛的应用。相信随着Java技术的不断进步和成熟,它必将在嵌入式系统中发挥越来越重要的作用。本文介绍了Java技术和嵌入式系统的特点,阐述了基于Java的嵌入式体系结构,最后分析了Java技术在嵌入式系统中的作用。     

基于Applet的Telnet功能与实现

介绍了在网络应用中日益重要的Java Applet所存在的优缺点，并由此讨论了产生这些优缺点的Java Applet安全模型的发展历程，进而分析了这种模型在安全性方面的优点，同时也指出了Java Applet给用户带来的不便。在分析了Java Applet安全模型结构后，提出了绕过这种安全模型实现远程登陆功能的系统架构，并列出了用Java Applet实现的基于Web的Telnet功能的部分代码。     

基于Applet的Telnet功能与实现

介绍了在网络应用中日益重要的Java Applet所存在的优缺点,并由此讨论了产生这些优缺点的Java Applet安全模型的发展历程,进而分析了这种模型在安全性方面的优点,同时也指出了Java Applet给用户带来的不便。在分析了JavaApplet安全模型结构后,提出了绕过这种安全模型实现远程登陆功能的系统架构,并列出了用Java Applet实现的基于Web的Telnet功能的部分代码。     

Java技术在嵌入式系统中的应用

J2ME是Java 2平台的一个版本,使用在各种各样的消费电子产品和嵌入式设备上。JavaCard技术规范使得Java应用能运行在智能卡和更小的嵌入式设备上。本文介绍J2ME和Java Card的硬件平台和软件体系结构,以及如何进行J2ME和Java Card应用程序开发。Java在移动通信领域的应用已经引起广泛的关注,本文对此进行了详细的描述。     

基于SNMP的嵌入式设备监控系统的设计与实现

SNMP是目前最为流行的网络管理解决方案,已广泛应用于网络设备的管理中。介绍SNMP的基本原理。提出一个基于SNMP的嵌入式设备监控系统模型。该系统使用基于Linux的嵌入式数据采集卡实现了SNMP代理端,并使用Java技术实现SNMP管理端。从而实现对被管设备的网络管理。     

Java虚拟机优化技术在移动通信设备中的应用研究

本文针对移动通信设备的硬件特点,分析了编译优化技术应用于嵌入式Java虚拟机上所面临的困难,提出了一套基于解释执行的嵌入式Java虚拟机性能优化方案,能够有效地提高Java虚拟机的性能。     

基于FPGA的Java处理器设计

针对Java技术在嵌入式领域的广泛应用,设计了一个适用于低端嵌入式设备的32位环境的Java处理器JPOR。该处理器由FPGA芯片实现,采用一种新的Java栈结构,指令系统简洁,可以直接执行Java字节码,能够对实时Java规范(RTSJ)提供有效支持。在Xilinx SPARTAN-3平台上通过了功能仿真,表明该Java处理器能够在低成本的FPGA芯片中实现。     

市场·市场劲报

IBM第一广义计算产品 IBM近日推出了一种用于嵌入式系统的新型应用开发工具集的beta测试版——VisualAge for Embedded Systoms,这是IBM计划于1999年投放市场的系列产品之一,旨在帮助客户实施广义计算,有助于开发商建立适用于嵌入式系统的Java应用。 在此之前,由于每种应用只能用于某种特定的设备,开发商每次只能创建一种应用,所以将产品推向市场的过程十分缓慢,而且费用极高。通过Java技术版的VisualAge for Embedded Systems,客户可以更快地开发借助Internet将小型智能设备与企业后端系统相连的软件应用。现在,开发商将可以利用Java技术与部件更快地向市场投入嵌入式系统应用。     

异类DAN的一致Web管理模型的研究

基于嵌入式Internet技术Web管理技术，针对各种设备域网络DAN(Device Atea Network)的一致化网络管理，提出了一个对异类设备域网络DAN进行一致管理的Web模型，解决了家庭、企业设备环境中异类网络的一致性管理、Web化管理等问题。该模型是一个以嵌入式设备网关和嵌入式网络网关为主框架的四层结构，集成了Java技术、SNMP协议(Simple Network Management Protocol)、WBDM(Web-based Device Management)管理模型中的EWS(Embedded Web Server)等技术，形成了一个开放的、通用性强的、跨平台的Web管理框架，为嵌入式系统管理员在任何时间和任何地点提供了友好的、平台无关的、易于使用的远程监控嵌入式设备的方法。     

Integrating Java 3D model and sensor data for remote monitoring and control

This paper presents a novel approach and a framework for web-based systems that can be used in distributed manufacturing environments. A prototype is developed to demonstrate its application to remote monitoring and control of a Tripod—one type of parallel kinematic machine. It utilizes the latest Java technologies (Java 3D and Java Servlets) as enabling technologies for system implementation. Instead of using a camera for monitoring, the Tripod is modeled using Java 3D with behavioral control nodes embedded. Once downloaded from its server, the 3D model behaves in the same way of its counterpart at client side. It remains alive by connecting with the Tripod through message passing, e.g., sensor signals and control commands transmissions. The goal of this research is to eliminate network traffic with Java 3D models, while still providing users with intuitive environments. In the near future, open-architecture devices will be web-ready having Java virtual machines embedded. This will make the approach more effective for web-based device monitoring and control.     

Jini-Java嵌入技术的新突破

Ｊａｖａ嵌入技术悄然兴起。而Ｊｉｎｉ技术的出现使得Ｊａｖａ在成功地为嵌入计算提供了合适的平台之后,更为嵌入计算设备,尤其是家用消费类电子设备提供了一个全新的网络计算结构。文章将较详细地介绍Ｊｉｎｉ系统的组成和结构。     

JAVACAM: trimming Java down to size

JavaCam is an embedded sensor device that connects to the Internet and operates with as little as 1.5 Mbytes of total system memory. To determine how small a Java system we could build that would still support a Java Virtual Machine, we wrote the Java Nanokernel, a very thin operating system. We then ported Sun's Java Development Kit 1.0.1 to JN. This port included the complete Java language and all of the core Java packages except java.awt. In this article, we begin by describing JN and the port of JDK 1.0.1 to it. We then describe our first significant application, JavaCam, a camera that is remotely programmable in Java and Internet accessible     

在嵌入式Java芯片中使用即时编译技术

Java虚拟机具有面向堆栈与面向对象的特点,不利于硬件有效支持字节码的直接执行,传统JIT也不适应嵌入式系统的应用环境,介绍了在自行设计的嵌入式Java芯片中使用JIT的技术途径,通过对Java虚拟机堆栈和复杂指令的支持,密切配合JIT软件,较好地解决了Java芯片设计中的问题。测试结果表明,相对于目前前界最好的picoJava-Ⅱ内核而言内核而言,JC401的编译后代码性能提高了1．2至1．9倍,在硬件复杂度、执行速度、内存开销等方面都有较大程度的改善,适合于嵌入式应用。     

Cross‐profiling for Java processors

Performance evaluation of embedded software is essential in an early development phase so as to ensure that the software will run on the embedded device's limited computing resources. The prevailing approaches either require the deployment of the software on the embedded target, which can be tedious and may be impossible in an early development phase, or rely on simulation, which can be very slow. In this article, we introduce a customizable cross‐profiling framework for embedded Java processors, including processors featuring a method cache. The developer profiles the embedded software in the host environment, completely decoupled from the target system, on any standard Java virtual machine, but the generated profiles represent the execution time metric of the target system. Our cross‐profiling framework is based on bytecode instrumentation. We identify several pointcuts in the execution of bytecode that need to be instrumented in order to estimate the CPU cycle consumption on the target system. An evaluation using the JOP embedded Java processor as target confirms that our approach reconciles high profile accuracy with moderate overhead. Our cross‐profiling framework also enables the performance evaluation of new processor architectures before they are implemented. As a case study, we explore the performance impact of various processor design choices and optimizations, such as different cache sizes or pipeline organizations, and come up with an improved processor design that yields speedups of up to 40% on standard Java benchmarks. Copyright © 2009 John Wiley & Sons, Ltd.     

Client ahead‐of‐time compiler for embedded Java platforms

Many embedded Java platforms execute two types of Java classes: those installed statically on the client device and those downloaded dynamically from service providers at run time. For achieving higher performance, the static Java classes can be compiled into machine code by ahead‐of‐time compiler (AOTC) in the server, and the translated machine code can be installed on the client device. Unfortunately, AOTC cannot be applicable to the dynamically downloaded classes. This paper proposes client‐AOTC (c‐AOTC), which performs AOTC on the client device using the just‐in‐time compiler (JITC) module installed on the device, obviating the JITC overhead and complementing the server‐AOTC. The machine code of a method translated by JITC is cached on a persistent memory of the device, and when the method is invoked again in a later run of the program, the machine code is loaded and executed directly without any translation overhead. A major issue in c‐AOTC is relocation because some of the address constants embedded in the cached machine code are not correct when the machine code is loaded and used in a different run; those addresses should be corrected before they are used. Constant pool resolution and inlining complicate the relocation problem, and we propose our solutions. The persistent memory overhead for saving the relocation information is also an issue, and we propose a technique to encode the relocation information and compress the machine code efficiently. We developed a c‐AOTC on Sun's CDC VM reference implementation, and our evaluation results indicate that c‐AOTC can improve the performance significantly, as much as an average of 12% for EEMBC and 4% for SpecJVM98, with a persistent memory overhead of 1% on average. Copyright © 2008 John Wiley & Sons, Ltd.     

基于J2ME的短消息管理系统

J2ME是SUN公司为了把Java应用于移动通信设备和嵌入式设备而推出的一项技术,也是目前移动通信运营商在部署3G移动增值服务时的首选技术。论述了采用J2ME和西门子移动开发工具包6688i设计开发短消息管理系统的方法和过程,通过12个操作类实现了短消息分组、短消息列表以及短消息内容编辑等短消息管理功能。     

嵌入式Java反射机制的设计与实现

Java反射是提高软件系统灵活性的重要技术,它是Java被视为动态语言的一个关键特性。虽然CLDC规范并不支持反射,但是在基于Java技术的嵌入式领域,反射仍有其应用需求。Sun公司根据CLDC规范发布了一套嵌入式Java技术的参考实现,其虚拟机被称作KVM。通过分析KVM的相关数据结构和机制,详细描述了反射机制的设计原理,并提出了一种在KVM中扩展反射功能的实现方案,经过测试证明该方案是可行的。     

Accessing embedded systems via WWW: the ProWeb toolset

The ubiquity of Web browsers makes them an ideal generic front end for simple client-server systems. A very suitable area of application is controlling embedded systems, such as network printers, where supporting standard Web browsers is a cost-effective and convenient alternative to developing custom client software for remote administration from different platforms.This paper describes the design and implementation of a flexible communication server to be run directly on the embedded system. It supports different protocols to allow remote access, including HTTP. Thus, the embedded system can be accessed with any Web browser. Its state is represented as a set of Web pages containing dynamically generated information. Java applets included in these Web pages can connect back to the server to subscribe to live data feeds for real-time visualization of the embedded system's state. A GUI builder implemented as a Java applet can be used to customize the visual appearance of these applets.     

TOWARDS THE CONSTRUCTION OF DECISIONAL DNA: A SET OF EXPERIENCE KNOWLEDGE STRUCTURE JAVA CLASS WITHIN AN ONTOLOGY SYSTEM

In this article, we present a Java class and an ontology system implementation for the exploitation of embedded experiential knowledge that can be used in several domains. We support this approach on three concepts: Set of Experience Knowledge Structure (SOEKS), a tool able to collect and manage explicit decisional knowledge; Decisional DNA, a structure for decisional knowledge akin to human DNA; and a group of ontologies for ubiquitous applications called SOUPA (Standard Ontology for Ubiquitous and Pervasive Applications).

The SOUPA is extended with the Set of Experience Knowledge Structure (SOEKS), enhancing the decisional experience used to assemble Decisional DNA with ontology characteristics for ubiquitous and pervasive applications. Additionally, we propose a SOEKS Java class created for the support and easy implementation of applications using the extended SOUPA which will allows the construction of a Decisional DNA repository useful within many different intelligent systems and platforms.